The present invention relates to dust bags for vacuum cleaners, and more particularly, to improved dust bags for upright vacuum cleaners used in health care facilities.
It has long been recognized that upright vacuum cleaners have superior cleaning characteristics as compared to canister type vacuum cleaners. However, upright vacuum cleaners have a disadvantage, as compared to canister type vacuum cleaners, in that the air emitted from upright vacuum cleaners is not filtered as efficiently as the air emitted from canister type vacuum cleaners. This disadvantage is particularly significant when the vacuum cleaners are utilized to clean hospitals and other health care facilities where it is very important to minimize the amount of dirt, dust and the like entrained in the air emitted from the vacuum cleaner.
As a result of their design, upright vacuum cleaners utilize a generally vertically disposed dirt collection or dust bag which has its lower end connected with the air discharge outlet of a motor driven fan mounted in the base of the vacuum cleaner and which has its upper end connected to and carried by the handle of the vacuum cleaner. The motor driven fan in the base of the vacuum cleaner forces air under pressure into the dust bag, and dust and dirt from the surface being cleaned is entrained in this air. The dust bag functions to "trap" or filter as much of this entrained dust and dirt as possible from the air before the air is emitted from the bag.
When originally introduced to the market, many of the upright vacuum cleaners used cloth or fabric dirt collection bags. Such bags were air pervious and the air introduced into the bag through the discharge outlet of the vacuum cleaner was forced out through the cloth or fabric. By its very nature, the cloth or fabric acted as a relatively good filter for the air passing therethrough. However, after usage, dirt and dust would become "trapped" in the cloth or fabric. This would increase the resistance to air passing through the cloth or fabric and, consequently, would reduce the cleaning efficiency of the vacuum cleaner. In addition, the cloth or fabric bags were difficult to clean, and because of their cost, it was not practical to replace rather than clean them.
To avoid the disadvantages of the cloth or fabric bags, it has become common practice to utilize an inner paper dirt collection bag disposed within a plastic outer bag. The lower end of the paper is connected directly to air discharge outlet of the vacuum cleaner so that the air from the motor driven fan is initially forced into the paper bag. The air flows out of the paper bag through the paper and then flows out of the plastic outer bag. The plastic used to make the outer bag is air pervious and frequently has a plurality of small holes therein to facilitate the air flow. Thus, for all practical purposes, the air emitted from the vacuum cleaner is only filtered as it passes through the inner paper bag.
This paper inner bag - plastic outer bag combination is attractive from a marketing standpoint, because the inner paper bags are relatively inexpensive to replace and when necessary, the plastic outer bag can be easily cleaned. However, the air filtering efficiency of this combination of bags is not as good as that afforded by cloth or fabric bags, and is particularly disadvantageous when the vacuum cleaner is utilized to clean hospitals, health care facilities and the like wherein the dirt and dust free environment is required and wherein the dust and dirt "picked up" in one room should not be spread throughout other rooms.
It is a primary object of my present invention to provide an improved dust bag which affords a significantly higher air filtering efficiency than prior dust bag and which consequently, is particularly adapted for use with upright vacuum cleaners utilized to clean hospitals, health care facilities and the like. More specifically, my improved dust bag includes an inner paper bag directly connected to the air discharge outlet of a vacuum cleaner and an outer bag made of air impervious material.
The outer bag has a relatively large opening therein which defines the flow path for the air flowing out from the interior of the bag. An inner wall divides the outer bag into two compartments and includes a second opening which is aligned with and which coincides, in size and shape, with the first opening. The inner paper bag is disposed in the compartment remote from the first opening, and a high efficiency air filter is disposed in the compartment adjacent to the first opening. The portion of the inner wall surrounding the second opening is biased against the filter so as to form an air seal therebetween thus assuring that the air flowing out of my improved dust bag passes through the filter.
The outer bag also includes two normally closed apertures which, when opened, permit facile replacement of the filter and the inner paper bag. Zipper type fasteners are used to close these two apertures and prevent air from escaping through these apertures when they are closed.
The filter includes filtering material supported about its periphery by a frame. The frame may have a generally rectangular shape or may be wedge shaped. When a wedge shaped filter is utilized, the compartment into which the filter is dispoed has a corresponding wedge shape so that the filter can be tightly fit within the compartment. An open mesh material extends over the first and second openings to constrain and support the filter material.
These and other objects of the present invention will become apparent from the following description of the preferred embodiment of my improved dust bag which is described in connection with the accompanying drawings.